Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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STORAGE TANK SYSTEM HAVING EASE OF PLACEMENT
AND INTERCONNECTIVITY
FIELD OF THE INVENTION
Embodiments described herein relate generally to one or more
storage tanks for liquids carrying debris, systems for fluid interconnection
of
multiple tanks and particular tank design enabling safe manoeuvring in
containment areas such as bermed areas.
BACKGROUND OF THE INVENTION
Typically, conventional storage tanks for drilling fluids or muds,
used in the oil and gas industry, have a rectangular planar geometry inside
the
tank including horizontal surfaces upon which debris carried in the mud can
settle
and accumulate. Often agitators are used during working of the tank or in
periodic maintenance including the use of pressured liquid or steam to
dislodge
debris. Such maintenance is time consuming and expensive.
Typical mud tanks weigh around 500,000 pounds and are normally
located in a spill containment area or berm. Berms are intended to capture
accidental loss of liquids from such tanks and integrity of the berm's liquid-
containing layer is critical. When placing such tanks, it is a known challenge
to
manoeuvre these tanks into place in the containment area without disturbing or
damaging the integrity of the floor of the berm. To date, Applicant is not
aware of
an effective and safe way to place tanks off of transport vehicles.
Conventional
cranes, pickers and swampers, not otherwise required on site, are very
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expensive to being in temporarily. There is a need to be able to use onsite
equipment to safely manoeuvre tanks with minimal risk to the berm integrity,
with
an objective to provide a time, safety and cost advantage.
SUMMARY OF THE INVENTION
Embodiments described herein are directed to a storage tank
comprising a bottom having a lower curved portion which is curved for urging
the
debris contained in the liquid stored in the tank to a base of the tank.
Embodiments described herein are also directed to various
systems associated with the tank such as debris-flush system, a manoeuvring
roller system and fluid connections between multiple tanks in a tank farm.
Accordingly in one broad aspect a storage tank system for the
storage of liquid, containing debris, is provided. The tank system comprises a
tank having a front wall and a back wall spaced longitudinally apart by two
sidewalls for defining an enclosed area for storing the liquid. Each sidewall
has
an upper portion and a curved lower portion forming a bottom. The curved lower
portion receives debris settling out of the liquid and directs at least some
of the
debris to a base of the bottom the tank. The system further comprises a
plurality
of nozzles spaced longitudinally along the curved lower portion of at least
one of
two sidewalls for directing flush liquid downwardly against the curved lower
portion for flushing any residual debris remaining thereon towards the base of
the
tank.
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Accordingly in another broad aspect a storage tank system having
manoeuvrable tanks in a containment area is provided. The tank system
comprises a tank having a bottom, a front wall and a back wall spaced
longitudinally apart by two sidewalls for defining an enclosed area for
storing the
liquid. The system also comprises a skid extending along the tank for
supporting
the bottom of the tank and engaging a floor of the containment area. The
system
further comprises rollers located along a bottom edge of the skid adjacent a
first
end of the tank. The first end can be either the front wall or the back wall.
The
rollers engage the floor and support the weight of the first end of the tank
in a
manoeuvring position for manoeuvring within the containment area when a
second end of the tank is lifted off the floor. The second end can be either
the
front wall or the back wall respectively.
Accordingly in another broad aspect a storage tank farm is
provided. The tank farm comprises a plurality of the tanks. Each tank has at
least
one interconnection means. Each tank is fluidly connected in parallel by at
least
an outlet to an adjacent tank using fluid conduits connected between the at
least
one interconnection means of each tank. In one embodiment, the interconnection
means is housed in a heated cabinet.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side view of a storage tank according to one
embodiment;
Figure 2 is an end view of the storage tank of Fig. 1;
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Figures 3A and 3B are end and side cross-sectional views,
respectively illustrating one embodiment of arrangement of nozzles of an
injection means inside the tank of Fig.1,
Figure 4 is a perspective view of the front wall of the inside of the
tank of Fig. 3B;
Figure 5 is a front view of low-profile rollers located along a bottom
edge of an end of the tank of Fig. 1;
Figures 6A, 6B and 6C illustrate positions of the tank of Fig. 1 with
respect to the low profile rollers during maneuvering of the tank inside a
berm
and after the tank have been positioned in the berm; more particularly Figs.
6A
and 6B are perspective side views of the tank in a manoeuvring position and a
resting position, respectively and Fig. 6C is a plan view of two tanks in a
resting
position and one tank being manoeuvred;
Figure 7 is a top perspective view of a tank farm comprising a
plurality of storage tanks connected in parallel and located in a berm
according to
another embodiment;
Figure 8 is a schematic view illustrating the interconnection means
of Fig. 7 between the adjacent tanks;
Figure 9 is a side view of the tank of Fig. 1 further illustrating
accessories such as a cabinet, wind detection means and lighting means
provided on the tank of Fig.1;
Figure 10 is a front view of one tank of Fig. 7 illustrating a cabinet
housing an interconnection means;
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Figure 11 is a side perspective view of the cabinet of Fig.10;
Figure 12 is a schematic illustration of a portion of a piping
arrangement;
Figure 13 is a perspective, side cross-sectional view of a storage
tank according to another embodiment; and
Figure 14 is a front perspective view of the tank of Fig. 13
illustrating an interconnection means located in a cabinet at a front wall of
the
tank.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Herein, embodiments are directed to improvements to mud-storage
tanks, such improvements including having superior debris handling, improved
manoeuvrability in a berm environment and improved interconnectability.
With reference to Figs. 1 and 2, one embodiment of a tank 1 is
shown for storing liquid such as drilling mud containing debris. The tank 1
comprises a liquid-containing volume defined by a bottom 2, a top wall 3, a
front
wall 4, a back wall 5 and sidewalls 6 defining an enclosed area 7. The front
wall 4
and the back wall 5 are spaced longitudinally apart by the sidewalls 6. Each
sidewall 6 has an upper portion 6a and a lower curved portion 6b. The lower
curved portion 6b receives debris settling out of the liquid and directs at
least
some of the debris settling on the curved portion of the bottom 2 to a base 2a
of
the tank. The curved portion 6b urges debris settling from the liquid towards
the
bottom 2 of the tank 1. The curved geometry of the lower portion 6b poses no
transition or interface to impede the movement of debris downward and toward
the middle and lowest part specifically the base 2b of the tank 1. This
minimizes
the accumulation of debris on the inside surfaces of the tank 1 and the
problems
associated therewith. In one embodiment, the lower curved portion 6b of the
tank 1 is semi-circular. Accordingly, as shown in Fig. 1, in another
embodiment,
the upper portion 6a is substantially vertical and the curved lower portion 6b
is
semi-circular. Accordingly, such a tank 1 has a D-shaped cross-section in a
transverse direction.
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Further, as shown in Figs. 3A and 3B, to aid in moving debris
downwardly, the curved lower portion 6b of at least one of the two sidewalls 6
of
the tank 1 is provided with a plurality of nozzles 9 spaced longitudinally
along the
curved lower portion 6b for directing flush liquid downwardly against the
curved
lower portion 6b for flushing any residual debris remaining thereon towards
the
base 2a of the tank. The nozzles 8 are angled such that the flush fluid
follows the
geometry of the lower curved portion 6b. A flush fluid-supply conduit 9a
supplies
flush fluid to the nozzles 8 and can extend longitudinally along the tank 1,
at an
elevation at about the transition from the side walls 6 to the bottom 2. The
flush
fluid can be clarified liquid or fresh liquid.
Each nozzle 9 can be manually adjusted to change their
orientation. In one embodiment, the nozzles 9 are angled at least downwardly
towards the bottom 2 of the tank, and as shown in Fig. 3A, also angled towards
the tank discharge or outlet 22, shown here as located adjacent the front wall
4 of
the tank 1 (see Fig. 3B). The nozzles 9 direct flush fluid towards the base 2a
and
towards the front wall 4 for urging debris towards the discharge 22.
Accordingly,
debris and mud are discouraged from settling or accumulating on these
surfaces.
Debris accumulated at the base 2a can be removed through the outlet 22. The
tank 1 can also be provided with hatches (not shown) for hand-removal of
debris.
Fig. 4 is an inside view of the tank 1 illustrating one embodiment of
the piping arrangement. Inlet 21 provides mud to the tank 1. Outlet 22
delivers
mud from the tank 1 to a pumping station (not shown). Outlet 22 can also be
used to remove debris settling out off the liquid in the tank 1. Flush fluid
is
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provided to the nozzles 9 by the flush fluid-supply conduit 9a. Float line 33
enables measurement of the liquid level in the tank 1. Steam lines 32 can heat
the liquid in the enclosed area 7, such as preventing the liquid from
freezing.
In another embodiment, as shown in Figs. 5, 6A, 6B and 6C, to aid
in manoeuvrability and placing of the tank, the tank 1 is provided with
rollers 10.
The rollers are located along a bottom edge 11 of a frame or skid 14 adjacent
a
first end 12 of the tank 1. In one embodiment, the first end 12 corresponds to
the
front wall 5. These rollers 10 aid in manoeuvring and positioning the tank 1
in a
containment area or berm 13 (seen in Fig. 6C) after the tank 1 has been
dropped
off a transport truck. The skid 14 normally engages the ground or floor of the
berm. The bottom of the tank 1 is supported in the skid 14 with suitable
supports
and structure. The skid 14 is typically a structure which extends
longitudinally
and laterally across a footprint of the tank 1. To permit manoeuvring without
lifting of the entirety of the tank 1, the rollers 10 are located for movably
supporting the first end 12 of the tank while lifting equipment lifts an
opposing
second end 15. The lifting equipment need only lift about one-half of the tank
weight with a safety margin in reserve.
Depending upon the stability of the lifting equipment, the rollers 10
can correspondingly be placed or distributed as necessary, across a width of
the
first end 12, to assist in side-to side-stability.
The rollers 10 can be operative between a manoeuvring position
and a resting position. The rollers 10 can be engaged in the manoeuvring
position and rendered inoperative in the resting position through their
relationship
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relative to the angle of the frame 14 when the tank 1 is alternated between
being
lifted, by lifting the second end 15, and being lowered to be placed
completely on
a floor 13a of the berm. The rollers 10 can be housed in a roller housing 10a
located in the skid 14. The rollers 10 are at least partially recessed
upwardly in
the roller housing 10a, having a low profile. The rollers 10 selectively
engage the
floor 13a, for movably supporting the tank 1, only when the second end 15 is
lifted. When the tank 1 is lowered, the tank's weight supported on the low-
profile
rollers 10 lessens and the rollers 10 may even become spaced from the floor
13a.
As shown in Figs. 6A, 6B and 6C, the floor 13a can be somewhat
protected using known rig mat systems 40. The rig mat system is a sectional,
rigid mat providing a robust surface which can be assembled over the floor 13a
of the berm 13. One or more barrier layers may also be laid between the rig
mat
40 and the floor 13a. When the tank 1 is placed in the berm 13 and has to be
manoeuvred, the tank is unloaded into the berm 13, to arrange the tank 1 in
the
berm or adjacent other tanks 1,1..... located in the berm 13. The tank 1 is
manoeuvred by lifting the second end 15 of the tank 1 (as seen in Fig. 6C) off
the
floor 13a of the berm 13 with a lifting equipment such as a medium duty
forklift 16
so that the low profile rollers 10 at the first end 12 engage rig mat system
40 or
the floor 13a. In this position (Fig. 6B) the first end 12 and the
corresponding
weight of the tank 1 is supported by the rollers 10. The tank 1 is rolled
along the
floor 13a, without damage to the rig mats or underlying floor, and is
manoeuvred
into position within the berm 13. The rollers 10 engage the floor 13a and
support
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the weight of the first end 12 of the tank 1 in a manoeuvring position for
manoeuvring within the containment area 13 when the second end 15 of the tank
is lifted off the floor 13a. The first end 12 and the second end 15 can be
located
either on the front wall 4 or the back wall 5. For a tank having a length of
46', the
rollers 10 are designed to movably engage the floor 13a with as little as an
18
inch lift at the second end 14. This means that large lifting equipment is not
required to lift the end 14. A medium duty forklift 16 can comfortably achieve
this
lift. The rollers 10 provide a safe, quick method of positioning the tank 1 in
the
berm 13, which usually has tight space constraints. The rollers 10 allow large
masses such as tanks weighing 500,000 pounds to be moved with much smaller
equipment, such as that already on-site and without need for special hire.
After
placement, the tank 1 is lowered, substantially relieving any weight on the
rollers
10 (as seen in Fig. 6A).
The movement of drilling fluids or mud to and from, and between,
tanks is aided, particularly in cold climates, by heating or maintaining some
heat
in the mud. Accordingly, in an embodiment, tanks are insulated on an exterior
of
the tank. Insulation is vulnerable to mechanical damage. Transport, handling
and manoeuvring of such tanks 1 can result in significant damage to exterior
insulation. The enclosed area 7 of the tank 1 can also be provided with a
steam
line for keeping the liquid from freezing.
In one embodiment and as seen in Figs. 1 and 2, an exterior of the
lower curved portion 6b is provided with an insulation layer 17. The exterior
of
the tank 1 is provided with plurality of ribs 18, spaced longitudinally along
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tank 1. Insulation 17 is located in the recess 18a formed between two adjacent
ribs 18, 18.
The ribs 18 aid in protecting the insulation 17 from much of the
longitudinal tearing and damage when the tank 1 is manoeuvred within tight
spaces such as the berm 13. The ribs 18 and insulation 17 can also extend
upward from the bottom 2 and along the side walls 6.
With reference to Fig. 7, in one embodiment, a plurality of tanks
1,1... can be arranged side-by-side in a tank farm 19 for increased capacity
and
facility. Each tank 1 in the farm 19 has fluid inlet and fluid outlet for
adding and
removing mud from the respective tank 1. Conventional tank farms typically
have
external hoses and connectors hooking the tanks together resulting in many
long
cumbersome hoses and fittings interconnecting all the tanks which are
vulnerable
to leaks and acting as tripping hazards.
With reference to Figs. 7and 8, an interconnection means 20, as
described herein, enables the tanks 1 to be fluidly connected in parallel for
fluid
operations to any one or more of the tanks 1. Each tank 1 and the
interconnection means 20 are configured for ease of connection, a tidy
arrangement of connecting fluid lines and flexibility of tank operations. Each
tank
1 is fluidly connected in parallel by at least an outlet to an adjacent tank
using
fluid conduits connected between the at least one interconnection means 20 of
each tank 1.
Fig. 8 illustrates a schematic representation of an embodiment of
the interconnection means 20. An end of each tank 1, such as the end 15, is
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provided with an inlet manifold 21 a and an outlet manifold 22a. The inlet
manifold
21a and outlet manifold 22a are in fluid communication with the tank 1. In one
embodiment and as seen in Figs. 4, and 7 to 11, the inlet and outlet manifolds
21a, 22b, are housed in a cabinet 26 located at the front wall 4 of the tank
1. A
first connection 20a is fluidly connected to the inlet manifold 21a at an
interface
26a of the cabinet 26. A second connection 20b is fluidly connected to the
inlet
manifold 21a at an interface 26a of the cabinet 26. Each tank 1 is further
provided with an inlet valve 23 between the inlet manifold 21 a and the tank I
and
an outlet valve between 24 between the outlet manifold 22a and the tank 1. The
inlet manifold 21a and the outlet manifold 22a of each tank have similar or
identical configurations to the inlet and outlet manifolds of adjacent tanks
1, of
the farm 19. The inlet manifold 21 and the outlet manifold 22 of a tank can be
readily connected to the inlet manifold 21 and the outlet manifold 22 by the
first
connections 20a and the second connections 20b. In one embodiment, the first
connections 20a and the second connections 20b are conduits. Such an
arrangement enables each tank 1 in the farm 19 to circulate, to receive and
dispense mud, independently or as a whole. Only one pump need be provided
for the whole tank farm 19. However, a redundant pump may be provided as a
backup. The interconnection means 20 simplifies the piping and reduces
chances of leaks as there are less connection points, valves and pipes.
As the interconnection means 20 is located in the cabinet 26, offset
from the ground, tripping hazards are eliminated. The cabinet 26, and in turn
the
interconnection means 20, can be heated to minimize the opportunity for the
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manifolds and the valves being frozen in cold climates. This ensures that the
tanks 1,1... in the farm 19 are reliably fluidly connected. In one embodiment,
the
cabinet 26 can be heated using a steam line 32 (as seen in Fig. 4).
In one embodiment and as seen in Figs. 7 and 9, the tank 1 is
provided with accessories such as a wind direction detection means 27 and
lighting means 28 which are telescopic. In one embodiment, the wind direction
detection means 27 is a windsock 27a located on a telescopic tube 27b
extending upwardly from the tank 1. The wind direction detection means 27 and
the lighting means 28 are designed to telescopically collapse or fold up so
that
the tank 1 can be transported with no external piping or protrusions beyond
standard transport limit.
Fig. 12 is a schematic illustration of an essential portion of the
piping arrangement of the tank of Fig. 1. Seen in Fig. 12 are the flush fluid-
supply
conduit 9a, the nozzles 9, the steam lines 32, the inlet manifold 21a and the
outlet manifold 22b. 35 is a fill line which is used to deliver liquid to the
tank 1
from a truck (not shown). The fill line 35 can be located outside the cabinet
26 as
the fill line 35 does not contain any stagnant fluid and not susceptible to
accidental freezing. In one embodiment, the inlet manifold 21a can also be
used
to deliver mud to the pumping station.
In one embodiment, the tank 1 is associated with a gauging
system, conduit 33 of Fig. 4 for determining the level of liquid in the tank
1.
Figs. 13 and 14 illustrate another embodiment of a storage tank.
Tank la is illustrated in Fig. 13 is identical to the tank 1 illustrated in
Figs. 1 to
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11 except that the enclosed area 7 of tank 1 a is divided into two independent
chambers. The enclosed area 7 of tank 1 a comprises at least one partition
plate
29 extending transversely between the sidewalls 6 for dividing the enclosed
area
7 into at least two independent chambers 30 and 31. The partition plate
extends
upwardly from the bottom 2 of the tank la for dividing the tank la into two
independent chambers 30 and 31. In one embodiment, the two chambers 30 and
31 store two different kinds of liquid. Liquid containing debris or used mud,
is
stored in the first independent chamber 30 which is defined by the partition
plate
29 and the front wall 4 of the tank 1a. As chamber 30 stores liquid containing
debris, the nozzles 9 are located in this chamber. Clear liquid or liquid not
containing debris, fresh mud or base fluids, is stored in the second
independent
chamber 31 which is defined by the partition plate 29 and the back wall 5 of
the
tank la. Since the liquid stored in chamber 31 does not contain debris, the
nozzles are not provided in this chamber. Chamber 31 is provided with a drain
plug 37. Chamber 31 is also provided with a line 38 for fluidly connecting the
chamber 31 to the inlet manifold 21 or outlet manifold 22 provided on the
front
surface 4 of the tank 1a. As seen in Fig. 14, the interconnection means
including
the inlet and outlet manifolds 21, 22 are housed in the cabinet 26 located at
the
front surface 4 of the tank 1.
The tank system described herein provides the following technical
advances: ability to be dismantled and moved with ease, ability to reduce
component count for valves, piping, circulation pumps, easy installation and
repair, increased safety of workplace, modular system to allow scalability,
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improved mud clean out methods, and improved positioning methods for
installation/tear down.
